There are various kinds of sensors used in touch panels of various electronic devices such as smart terminals, mobile phones, monitors, and TVs. Recently, various functions have been implemented using an optical sensor including a light emitter for emitting light and a light receiver for sensing light.
Hereinafter, a typical dust sensor will be described with reference to an accompanying drawing.
FIG. 1 is a cross-sectional view schematically showing a typical dust sensor 100.
The dust sensor 100 shown in FIG. 1 may consist of a light source 110, a lens 120, a mirror 122, a light receiver 130, and a light shield 140.
In the typical dust sensor 100 shown in FIG. 1, light emitted from the light source 110 is scattered by the dust 121 after passing through the lens 120. Then, the scattered light is incident on the light receiver 130. In this way, the typical dust sensor 100 checks various kinds of information such as the size, concentration, and amount of the dust 121 contained in the air using light. In the typical dust sensor 100, the light receiver 130 is disposed only on one side of the space where light is scattered. Specifically, the light receiver 130 is positioned in an area at 90° around the center of the space in which the dust 121 is sensed.
As shown in FIG. 1, according to a result of pre-conducted testing and simulation, when the light receiver 130 is disposed in an area at 90° around the center of the space where the dust is sensed, the intensity of the scattered light scattered by the dust 121 and incident on the light receiver 130 is not sufficiently high. Accordingly, the typical dust sensor 100 may not accurately receive the scattered light, and thus may not acquire correct information on the dust 121 due to low sensing sensitivity. Particularly, since the area of the light receiver 130 is very small, a cost for designing a separate circuit for amplifying the scattered light when an absorption amount of scattered light is insufficient may increase. Further, in the case of the typical dust sensor 100, the size of the dust sensor 100 may increase because the volume of the light receiver 130 is increased in order to increase sensing sensitivity.